Electrophotographic toner, process for preparing the same, image forming method and apparatus using the toner

ABSTRACT

Provided are an electrophotographic toner, a process for preparing the same, image forming method and an image forming apparatus using the toner. The electrophotographic toner may include a latex, colorant, wax, Si and Fe. A molar ratio of Si/Fe may be about 0.1 to about 5.

CROSS-REFERENCE TO RELATED PATENT APPLICATION

This application claims the benefit of Korean Patent Application No.10-2008-0067827, filed on Jul. 11, 2008 in the Korean IntellectualProperty Office, the disclosure of which is incorporated by referenceherein in its entirety.

TECHNICAL FIELD

This disclosure generally relates to the field of electrophotographicprinting. In particular, it is an electrophotographic toner, a processfor preparing the same, an image forming method and an image formingapparatus both using the toner.

BACKGROUND

In electrophotographic or electrostatic recording processes, a developerused to form an electrostatic image or an electrostatic latent image canbe classified into the following categories: (1) a two-componentdeveloper formed of toner and carrier particles; and (2) and aone-component developer formed of toner only. The one-componentdeveloper can be further classified into a magnetic one-componentdeveloper and a nonmagnetic one-component developer. Fluiding agentssuch as colloidal silica are often added to the nonmagneticone-component developer to increase the fluidity of the toner.Typically, coloring particles obtained by dispersing a pigment such ascarbon black or other additives in latex are used as the toner.

Methods of preparing toner include pulverization and polymerization. Inpulverization, toner is obtained by melting and mixing synthetic resinswith pigments and, if required, other additives. This mixture is thenpulverized and the particles are sorted until particles of a desiredsize are obtained. In polymerization, a polymerizable monomercomposition is manufactured by uniformly dissolving or dispersingvarious additives such as a pigment, a polymerization initiator and, ifrequired, a cross-linking agent and an antistatic agent in apolymerizable monomer. Then, the polymerizable monomer composition isdispersed in an aqueous dispersive medium, which includes a dispersionstabilizer. An agitator is used to shape any minute liquid dropletparticles. Subsequently, the temperature is increased and suspensionpolymerization is performed to obtain polymerized toner having coloredpolymer particles of a desired size.

In an image forming apparatus such as an electrophotographic apparatusor an electrostatic recording apparatus, an image is formed by exposingan image on a uniformly charged photoreceptor to form an electrostaticlatent image, attaching toner to the electrostatic latent image to forma toner image, transferring the toner image onto a transfer member suchas transfer paper or the like, and then fusing the toner image onto thetransfer member using any of a variety of methods, including heating,pressurizing, solvent steaming, and the like. In most fusing processes,the transfer medium with the toner image passes through fusing rollers.By heating and pressing, the toner image is fused to the transfermedium.

Images formed by an image forming apparatus such as anelectrophotocopier should satisfy requirements of high precision andaccuracy. Conventionally, toner used in an image forming apparatus isobtained by pulverization. In pulverization, color particles having alarge range of sizes may be formed. To obtain satisfactory developingproperties, the color particles must be sorted according to size toreduce the particle size distribution. However, it is difficult toprecisely control the particle size and the particle size distributionusing a conventional mixing/pulverizing process in the manufacture oftoner suitable for an electrophotographic process or an electrostaticrecording process. Also, when preparing a fine-particle toner, the tonerpreparation yield is adversely affected by the sorting process. Inaddition, there are limits to changes or adjustments that can be made tothe toner design while still obtaining desirable charging and fusingproperties.

Using polymerization, the size of particles is easier to control. Inaddition, these particles do not need to undergo a complex manufacturingprocess such as sorting. Polymerized toner having a desired particlesize and particle size distribution can be obtained without pulverizingor sorting. However, the particle size and shape are not alwayssatisfactorily controlled. In addition, it is not always easy toagglomerate latex and colorant. Further, an aluminum-based material maybe used as an agglomerating agent, which is hazardous to human healthand the environment. Also, since the toner has a narrower fusing rangeas the printing speed increases, toner having different fusingproperties according to the printing speed, may be needed.

Therefore, there is a need for toner that is efficiently agglomerated,presents little or no risk to humans or the environment, forms imageshaving high glossiness, has a wide fusing range during a high-speedprinting operation, has a fine particle size and reduced particle sizedistribution and has excellent heat preserving and anti-offsetproperties.

SUMMARY

We provide an electrophotographic toner comprising a latex, a colorant,a wax and about 3 to about 1,000 ppm each of Si and Fe. A molar ratio ofSi/Fe may be in the range of about 0.1 to about 5. Fusing properties ofthe electrophotographic toner satisfy Formulas 1 and 2:

$\begin{matrix}{\frac{M\; F\; T_{A}}{M\; F\; T_{B}} \geq {\frac{{HOT}_{A}}{{HOT}_{B}} \times 0.8}} & {{Formula}\mspace{14mu} 1} \\{{\frac{M\; F\; T_{A}}{M\; F\; T_{B}} \times {Gloss}_{A}} \geq {\frac{{HOT}_{A}}{{HOT}_{B}} \times 4}} & {{Formula}\mspace{14mu} 2}\end{matrix}$

MFT_(A) is a minimum fusing temperature in a low-speed printingoperation conducted at a rate of about 160 mm/sec. MFT_(B) is a minimumfusing temperature in a high-speed printing operation conducted at arate of about 290 mm/sec. HOT_(A) is a hot offset temperature in alow-speed printing operation conducted at a rate of about 160 mm/sec.HOT_(B) is a hot offset temperature in a high-speed printing operationconducted at a rate of about 290 mm/sec. Gloss_(A) is glossinessmeasured at an angle of about 60° at a fusing temperature of about 160°C. in a low-speed printing operation conducted at a rate of about 160mm/sec.

We also provide a method for preparing an electrophotographic toner. Themethod comprises preparing a first agglomerated toner by mixing firstlatex particles. The first latex particles comprise a wax with a pigmentdispersion. A metal salt of Si and Fe is then added to the mixture. Asecond agglomerated toner may be prepared by agglomerating fineparticles by coating a second latex on the first agglomerated toner. Thefusing properties of the electrophotographic toner satisfy Formulas 1and 2:

$\begin{matrix}{\frac{M\; F\; T_{A}}{M\; F\; T_{B}} \geq {\frac{{HOT}_{A}}{{HOT}_{B}} \times 0.8}} & {{Formula}\mspace{14mu} 1} \\{{\frac{M\; F\; T_{A}}{M\; F\; T_{B}} \times {Gloss}_{A}} \geq {\frac{{HOT}_{A}}{{HOT}_{B}} \times 4}} & {{Formula}\mspace{14mu} 2}\end{matrix}$

MFT_(A) is a minimum fusing temperature in a low-speed printingoperation conducted at a rate of about 160 mm/sec. MFT_(B) is a minimumfusing temperature in a high-speed printing operation conducted at arate of about 290 mm/sec. HOT_(A) is a hot offset temperature in alow-speed printing operation conducted at a rate of about 160 mm/sec.HOT_(B) is a hot offset temperature in a high-speed printing operationconducted at a rate of about 290 mm/sec. Gloss_(A) is glossinessmeasured at an angle of 60° at a fusing temperature of 160° C. in alow-speed printing operation conducted at a rate of about 160 mm/sec.

We also provide a method of forming images. The method comprisesattaching a toner to a surface of a photoreceptor on which anelectrostatic latent image has been formed to form a visible image andtransferring the visible image to a transfer medium. The toner is anelectrophotographic toner comprising a latex, a colorant, a wax, andabout 3 to about 1,000 ppm each of Si and Fe. A molar ratio of Si/Fe isin the range of about 0.1 to about 5. Fusing properties of theelectrophotographic toner satisfy Formulas 1 and 2:

$\begin{matrix}{\frac{M\; F\; T_{A}}{M\; F\; T_{B}} \geq {\frac{{HOT}_{A}}{{HOT}_{B}} \times 0.8}} & {{Formula}\mspace{14mu} 1} \\{{\frac{M\; F\; T_{A}}{M\; F\; T_{B}} \times {Gloss}_{A}} \geq {\frac{{HOT}_{A}}{{HOT}_{B}} \times 4}} & {{Formula}\mspace{14mu} 2}\end{matrix}$

MFT_(A) is a minimum fusing temperature in a low-speed printingoperation conducted at a rate of about 160 mm/sec. MFT_(B) is a minimumfusing temperature in a high-speed printing operation conducted at arate of about 290 mm/sec. HOT_(A) is a hot offset temperature in alow-speed printing operation conducted at a rate of about 160 mm/sec.HOT_(B) is a hot offset temperature in a high-speed printing operationconducted at a rate of about 290 mm/sec. Gloss_(A) is glossinessmeasured at an angle of 60° at a fusing temperature of about 160° C. ina low-speed printing operation conducted at a rate of about 160 mm/sec.

We also provide an image forming device comprising a photoreceptor, animage forming unit that forms an electrostatic latent image on a surfaceof the photoreceptor, a unit that receives toner, a toner supplying unitthat supplies the toner onto the surface of the photoreceptor in orderto form a toner image by developing the electrostatic latent image and atoner transferring unit that transfers the toner image to a transfermedium from the surface of the photoreceptor. The toner is anelectrophotographic toner comprising a latex, a colorant, a wax, andabout 3 to about 1,000 ppm each of Si and Fe. A molar ratio of Si/Fe isin the range of about 0.1 to about 5. Fusing properties of theelectrophotographic toner satisfy Formulas 1 and 2:

$\begin{matrix}{\frac{M\; F\; T_{A}}{M\; F\; T_{B}} \geq {\frac{{HOT}_{A}}{{HOT}_{B}} \times 0.8}} & {{Formula}\mspace{14mu} 1} \\{{\frac{M\; F\; T_{A}}{M\; F\; T_{B}} \times {Gloss}_{A}} \geq {\frac{{HOT}_{A}}{{HOT}_{B}} \times 4}} & {{Formula}\mspace{14mu} 2}\end{matrix}$

MFT_(A) is a minimum fusing temperature in a low-speed printingoperation conducted at a rate of about 160 mm/sec. MFT_(B) is a minimumfusing temperature in a high-speed printing operation conducted at arate of about 290 mm/sec. HOT_(A) is a hot offset temperature in alow-speed printing operation conducted at a rate of about 160 mm/sec.HOT_(B) is a hot offset temperature in a high-speed printing operationconducted at a rate of about 290 mm/sec. Gloss_(A) is glossinessmeasured at an angle of 60° at a fusing temperature of 160° C. in alow-speed printing operation conducted at a rate of 160 mm/sec.

We also provide a developing device comprising a photoreceptor, adeveloping unit that transfers toner onto the surface of thephotoreceptor, a toner supplying unit that supplies the toner to thedeveloping unit and a toner storing unit that stores the toner to besupplied to the toner supplying unit. The toner is anelectrophotographic toner comprising a latex, a colorant, a wax, andabout 3 to about 1,000 ppm each of Si and Fe. A molar ratio of Si/Fe isin the range of about 0.1 to about 5. Fusing properties of theelectrophotographic toner satisfy Formulas 1 and 2:

$\begin{matrix}{\frac{M\; F\; T_{A}}{M\; F\; T_{B}} \geq {\frac{{HOT}_{A}}{{HOT}_{B}} \times 0.8}} & {{Formula}\mspace{14mu} 1} \\{{\frac{M\; F\; T_{A}}{M\; F\; T_{B}} \times {Gloss}_{A}} \geq {\frac{{HOT}_{A}}{{HOT}_{B}} \times 4}} & {{Formula}\mspace{14mu} 2}\end{matrix}$

MFT_(A) is a minimum fusing temperature in a low-speed printingoperation conducted at a rate of about 160 mm/sec. MFT_(B) is a minimumfusing temperature in a high-speed printing operation conducted, at arate of about 290 mm/sec. HOT_(A) is a hot offset temperature in alow-speed printing operation conducted at a rate of 160 mm/sec. HOT_(B)is a hot offset temperature in a high-speed printing operation conductedat a rate of about 290 mm/sec. Gloss_(A) is glossiness measured at anangle of 60° at a fusing temperature of 160° C. in a low-speed printingoperation conducted at a rate of about 160 mm/sec.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages will become more apparent bydescribing in detail examples thereof with reference to the attacheddrawing in which FIG. 1 illustrates an image forming apparatus employingtoner.

DETAILED DESCRIPTION

The disclosure will now be described more fully. Reference may be madeto the accompanying drawing, in which representative example of an imageforming apparatus employing toner is shown.

An electrophotographic toner may include a latex, a colorant, a wax andabout 3-1,000 ppm each of Si and Fe. A molar ratio of Si/Fe may be inthe range of about 0.1 to 5. Fusing properties of theelectrophotographic toner may satisfy Formulas 1 and 2:

$\begin{matrix}{\frac{M\; F\; T_{A}}{M\; F\; T_{B}} \geq {\frac{{HOT}_{A}}{{HOT}_{B}} \times 0.8}} & {{Formula}\mspace{14mu} 1} \\{{\frac{M\; F\; T_{A}}{M\; F\; T_{B}} \times {Gloss}_{A}} \geq {\frac{{HOT}_{A}}{{HOT}_{B}} \times 4}} & {{Formula}\mspace{14mu} 2}\end{matrix}$

MFT_(A) is a minimum fusing temperature in a low-speed printingoperation conducted at a rate of about 160 mm/sec. MFT_(B) is a minimumfusing temperature in a high-speed printing operation conducted at arate of about 290 mm/sec. HOT_(A) is a hot offset temperature in alow-speed printing operation conducted at a rate of about 160 mm/sec.HOT_(B) is a hot offset temperature in a high-speed printing operationconducted at a rate of about 290 mm/sec. Gloss_(A) is glossinessmeasured at an angle of about 60° at a fusing temperature of about 160°C. in a low-speed printing operation conducted at a rate of 160 mm/sec.The minimum fusing temperature and the hot offset temperature weremeasured using a belt-type fusing device having a Nip width of 10 mm, aNip pressure of 4 kgf and paper (e.g., Exclusive, Xerox™) having aweight of 90 g/m².

Formulas 1 and 2 show relationships between the minimum fusingtemperature ratio and the hot offset temperature ratio of the low-speedand high-speed printings. If toner satisfies the relations representedby Formulas 1 and 2 at the same time, the toner has the required fusingproperties regardless of the printing speed of toner. That is, thefusing range of the low-speed fusing operation is not decreased in thehigh-speed fusing operation. Since the fusing range is stably maintainedduring the high-speed printing, the same toner may be adequate for bothlow-speed and high-speed fusing devices.

The fusing properties of the electrophotographic toner may be improvedby controlling an agglomeration process. A stable fusing range may beobtained by the anti-offset properties of toner. The anti-offsetproperties of toner are closely related to the rheological properties oftoner. In order to improve the rheological properties of toner, physicalproperties such as molecular weight of latex and cross-linking densityare regulated or wax is used as a releasing agent. However, the fusingrange may be reduced in the high-speed fusing process.

An agglomerating agent controls an agglomeration process to improve theTheological properties of toner. Thus, the fusing range in thehigh-speed printing operation may not be reduced at all or as severely.That is, toner elements such as the latex, the wax, and the colorant mayefficiently agglomerate using a metal salt agglomerating agent includingSi and Fe at a low temperature using a small amount of the metal salt.Since the rheological properties of toner can be improved by regulatingthe agglomeration process, a wide fusing range may be obtained duringthe high-speed printing operation and images having high glossinessoften result. In addition, capsule-shaped toner can be prepared byregulating the agglomeration process and, thus, the charging propertiesmay be uniformly regulated. Fluidity and heat preserving properties ofthe toner may be improved by inhibiting the colorant and pigment frombeing exposed.

A maximum glossiness difference of the electrophotographic toner betweenlow-speed printing, conducted at a rate of about 160 mm/sec, andhigh-speed printing, conducted at a rate of about 290 mm/sec, is lessthan about 3, and preferably in the range of about 0 to 2, when an imageis fixed using a belt-type fusing device (such a device may have a nipwidth of 10 mm, and line pressure of 4 kgf) and a TMA of 0.7±0.03mg/cm². Glossiness is measured using a glossmeter (micro-TR1-gloss) atan angle of 60°.

Since a metal salt including Si and Fe is used as an agglomerating agentin the manufacturing process of the electrophotographic toner, theelectrophotographic toner includes about 3 to about 1,000 ppm of each ofSi and Fe. When the concentration of Si and Fe, respectively, is lessthan 3 ppm, desired effects may not be obtained. On the other hand, whenthe concentration of Si and Fe, respectively, is greater than about1,000 ppm, problems such as charge reduction may occur.

When the electrophotographic toner is measured using a differentialscanning calorimeter, a starting point of the highest endothermic peakis in the range of 68 to 75° C., the peak temperature is in the range of75 to 95° C. and one or two endothermic peaks may be observed.

When the electrophotographic toner is measured using a differentialscanning calorimeter, a starting point of the highest endothermic peakis in the range of 68 to 75° C., the peak temperature is in the range of75 to 95° C. and one or two endothermic peaks may be observed.

When the metal salt including Si and Fe is used as an agglomeratingagent in the manufacturing process of the electrophotographic toner, amolar ratio of Si and Fe (Si/Fe) may be in the range of about 0.1 to 5,and preferably about 0.15 to 3. If the molar ratio of Si/Fe is less than0.1, a reduction in cohesion of toner may result. On the other hand,when the molar ratio of Si/Fe is greater than 5, charge reduction mayoccur.

Fine-particle toner may be prepared by using a metal salt including Siand Fe as an agglomerating agent and particle size of the toner may beregulated. Accordingly, an average particle size of the toner may be inthe range of about 3 to 8 μm, and an average sphericity of the toner isin the range of about 0.940 to 0.970. In particular, the averagesphericity difference between toner having the average particle size of2 μm and 5 μm may be less than 0.02, and thus the particles are moreuniform. In particular, PSD(p,v) values may be about 1.25 or less, andpreferably from about 1.23 to 1.2.

The electrophotographic toner has a storage modulus G′ in the range ofabout 1E+05 to 1E+07 at about 80° C., and in the range of about 5E+02 to3E+03 at 140° C. Thus, if the storage modulus G′ is less than about1E+05 at about 80° C., high temperature retention properties (storagestability, thermal endurance, and anti-blocking properties) may not bemaintained. If the storage modulus G′ is greater than about 1E+07 at 80°C., fusing properties (MFT) may not be maintained. If the storagemodulus G′ is less than about 5E+02 at about 140° C., anti-hot offsetproperties may not be maintained. If the storage modulus G′ is greaterthan about 3E+03 at about 140° C., toner may not have high glossiness.

We also provide a process for preparing an electrophotographic tonerwhereby agglomeration of toner can be efficiently achieved by using ametal salt including Si and Fe as an agglomerating agent.

The process includes: preparing a first agglomerated toner by mixingfirst latex particles including a wax, with a pigment dispersion, andadding a metal salt including Si and Fe to the mixture; and preparing asecond agglomerated toner by coating a second latex prepared bypolymerizing one or more polymerizable monomers, on the firstagglomerated toner.

It is believed that the size of the first agglomerated toner is madelarger by increased ionic strength resulting from the addition of themetal salt, including Si and Fe, and collisions between the particlesduring the process for manufacturing the toner. An example of the metalsalt is polysilica iron. In particular, products of

(

) (Model Nos. PSI-025, PSI-050, PSI-075, PSI-100, PSI-200 and PSI-300)can be used. Properties and compositions of PSI-025, PSI-050, PSI-075,PSI-100, PSI-200, and PSI-300 are listed in Table 1 below.

TABLE 1 PSI-025 PSI-050 PSI-075 PSI-100 PSI-200 PSI-300 Molar ratio ofSilica/Fe (Si/Fe) 0.25 0.5 0.75 1 2 3 Concentration of Fe(wt %) 5.0 3.52.5 2.0 1.0 0.7 main component SiO₂(wt %) 1.4 1.9 2.0 2.2 pH (1 w/v %)2-3 Specific gravity (20° C.) 1.14 1.13 1.09 1.08 1.06 1.04 Viscosity(mPa · S) 2.0 or higher Mean molecular weight (Dalton) 500,000Appearance Yellowish brown transparent liquid

The first latex particles may be polyester. In particular, they may be apolymer obtained by polymerizing one or more polymerizable monomers or amixture thereof (a hybrid type). When the polymer is used as the firstlatex particles, the polymerizable monomers can be polymerized with awax, or a wax can be added to the polymer. A wax-containing latex havinga particle size of about 1 μm or less, and preferably in the range ofabout 100 to 300 nm. can be prepared by emulsion polymerization.

The polymerizable monomer may be at least one monomer selected from thegroup consisting of styrene-based monomers such as styrene, vinyltoluene and α-methyl styrene; acrylic acid or methacrylic acid;derivatives of (metha)acrylates such as methyl acrylate, ethyl acrylate,propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, dimethylaminoethyl acrylate, methyl methacrylate, ethyl methacrylate, propylmethacrylate, butyl methacrylate, 2-ethylhexyl methacrylate,dimethylaminoethyl methacrylate, acrylonitrile, methacrylonitrile,acrylamide and metacryl amide; ethylenically unsaturated monoolefinssuch as ethylene, propylene and butylene; halogenized vinyls such asvinyl chloride, vinylidene chloride and vinyl fluoride; vinyl esterssuch as vinyl acetate and vinyl propionate; vinyl ethers such as vinylmethyl ether and vinyl ethyl ether; vinyl ketones such as vinyl methylketone and methyl isoprophenyl ketone; and nitrogen-containing vinylcompounds such as 2-vinylpyridine, 4-vinylpyridine and N-vinylpyrrolidone.

The wax used in the process of preparing the first latex or tonerfunctions to allow the toner to be fixed on a final image receptor at alow temperature and have excellent durability and wear resistance.Examples of the wax are polyethylene-based wax, polypropylene-based wax,silicone wax, paraffin-based wax, ester-based wax, carbauna wax andmetallocene wax, but are not limited thereto. In particular, the waxused in the toner may have a melting point in the range of about 50 toabout 150° C. Components of the wax may physically adhere to tonerparticles, but do not covalently bond to the toner particles.

The amount of wax may be about 0 to about 20 parts by weight based on100 parts by weight of the toner. When the amount of wax is greater thanabout 20 parts by weight based on 100 parts by weight of the toner, themanufacturing costs may increase. The wax may be added to the process ofpreparing the latex, or to the agglomeration process in a dispersedstate.

A polymerization initiator and a chain transfer agent may be used in theprocess of preparing the first latex to improve the efficiency of thepolymerization. Examples of the polymerization initiator are persulfatesalts such as potassium persulfate and ammonium persulfate; azocompounds such as 4,4-azobis(4-cyano valeric acid),dimethyl-2,2′-azobis(2-methyl propionate),2,2-azobis(2-amidinopropane)dihydrochloride, 2,2-azobis-2-methyl-N-1,1-bis(hydroxymethyl)-2-hydroxyethylpropioamide, 2,2′-azobis(2-4-dimethylvaleronitrile), 2,2′-azobis isobutyronitrile and1,1′-azobis(1-cyclohexanecarbonitrile); and peroxides such as methylethyl peroxide, di-t-butylperoxide, acetyl peroxide, dicumyl peroxide,lauroyl peroxide, benzoyl peroxide, t-butylperoxy-2-ethyl hexanoate,di-isopropyl peroxydicarbonate and di-t-butylperoxy isophthalate. Also,an oxidization-reduction initiator in which the polymerization initiatorand a reduction agent are combined, may be used.

A chain transfer agent is a material that converts a type of chaincarrier in a chain reaction. A new chain has generally much lessactivity than that of a previous chain. The polymerization degree of themonomer can be reduced and new chains can be initiated using the chaintransfer agent. In addition, a molecular weight distribution can beadjusted using the chain transfer agent.

Examples of the chain transfer agent are sulfur containing compoundssuch as dodecanthiol, thioglycolic acid, thioacetic acid andmercaptoethanol; phosphorous acid compounds such as phosphorous acid andsodium phosphite; hypophosphorous acid compounds such as hypophosphorousacid and sodium hypophosphite; and alcohols such as methyl alcohol,ethyl alcohol, isopropyl alcohol and n-butyl alcohol, but are notlimited thereto.

The first latex particles may further include a charge control agent.The charge control agent used herein may be a negative charge typecharge control agent or a positive charge type charge control agent. Thenegative charge type charge control agent may be an organic metalcomplex or a chelate compound such as an azo dye containing chromium ora mono azo metal complex; a salicylic acid compound containing metalsuch as chromium, iron and zinc; or an organic metal complex of anaromatic hydroxycarboxylic acid and an aromatic dicarboxylic acid.Moreover, any known negative charge type charge control agent may beused without limitation. The positive charge type charge control agentmay be a modified product such as nigrosine and a fatty acid metal saltthereof and an onium salt including a quaternary ammonium salt such astributylammonium 1-hydroxy-4-naphthosulfonate and tetrabutylanmoniumtetrafluoro borate which may be used alone or in combination of at leasttwo. Since the charge control agent stably supports toner on adeveloping roller by electrostatic force, charging may be performedstably and quickly using the charge control agent.

The prepared first latex may be mixed with a pigment dispersion. Thepigment dispersion can be prepared by homogeneously dispersing acomposition including pigments such as black, cyan, magenta and yellowand an emulsifier using a ultrasonic processor, Micro fludizer, or thelike.

Carbon black or aniline black may be used as the pigment for a blacktoner, and for color toner, at least one of yellow, magenta and cyanpigments are further included.

A condensation nitrogen compound, an isoindolinone compound, ananthraquine compound, an azo metal complex or an allyl imide compoundcan be used as the yellow pigment. In particular, C.I. pigment yellow12, 13, 14, 17, 62, 74, 83, 93, 94, 95, 109, 110, 111, 128, 129, 147,168, 180, or the like can be used.

A condensation nitrogen compound, an anthraquine compound, aquinacridone compound, a base dye lake compound, a naphthol compound, abenzo imidazole compound, a thioindigo compound or a perylene compoundcan be used as the magenta pigment. In particular, C.I. pigment red 2,3, 5, 6, 7, 23, 48:2, 48:3, 48:4, 57:1, 81:1, 122, 144, 146, 166, 169,177, 184, 185, 202, 206, 220, 221, 254, or the like can be used.

A copper phthalocyanine compound and derivatives thereof, an anthraquinecompound, or a base dye lake compound can be used as the cyan pigment.In particular, C.I. pigment blue 1, 7, 15, 15:1, 15:2, 15:3, 15:4, 60,62, 66, orthe like can be used.

Such pigments can be used alone or in a combination of at least twopigments, and are selected in consideration of color, chromacity,luminance, resistance to weather, dispersion capability in toner, etc.

The amount of pigment as described above may be about 0.1 to 20 parts byweight based on 100 parts by weight of the first latex. The amount ofpigment should be sufficient to color the toner; however, when theamount of the pigment is less than about 0.1 parts by weight based on100 parts by weight of the first latex, the coloring effect is notsufficient. On the other hand, when the amount of the pigment is greaterthan about 20 parts by weight based on 100 parts by weight of the firstlatex, the manufacturing costs of toner increase, and thus a sufficientamount of frictional charge cannot be obtained.

Any emulsifier that is known in the art may be used as an emulsifier inthe pigment dispersion. In this regard, an anionic reactive emulsifier,a nonionic reactive emulsifier or a mixture thereof can be used. Theanionic reactive emulsifier may be HS-10 (Dai-ich kogyo, Co., Ltd.),Dawfax 2-A1 (Dow Chemical Company), etc., and the nonionic reactiveemulsifier may be RN-10 (Dai-ichi kogyo, Co., Ltd.).

The prepared first latex particles including wax and the pigmentdispersion are mixed and then the agglomerating agent including Si andFe is added to the mixture to prepare agglomerated toner. Moreparticularly, the first latex particles including a wax and the pigmentdispersion are mixed, the agglomerating agent including Si and Fe isadded to the mixture at a pH of 1 to 4. This forms a first agglomeratedtoner having an average particle size of about 2.5 μm or less, whichbecomes a core of the toner. Then, a second latex is added to theresultant, and the pH is adjusted to 6 to 8. When the particle size isconstantly maintained for a certain period of time, the resultant isheated to a temperature in the range of about 90 to 96° C., and the pHis adjusted to 5.8 to 6 to prepare a second agglomerated toner.

The second latex may be prepared by polymerizing one or morepolymerizable monomers described above. The polymerizable monomers areemulsion polymerized to prepare latex having a particle size of lessthan about 1 μm; preferably in the range of about 100 to 300 μm. Thesecond latex may also include a wax and the wax may be added to thesecond latex in the polymerization process.

A third latex prepared by polymerizing one or more polymerizablemonomers described above may be coated on the second agglomerated toner.

By forming a shell layer with the second latex and/or the third latex,durability can be improved, which reduces storage problems duringshipping and handling.

The prepared second agglomerated toner or third agglomerated toner isfiltered to separate toner particles and the toner particles are dried.The dried toner particles are subjected to a surface treatment processusing silica or the like, and charge amount is controlled to prepare afinal dry toner.

The molecular weight, Tg and rheological properties of the first latexparticles formed in the core of toner prepared according to the methoddescribed above may be adjusted to efficiently fix toner particles at alow temperature.

The volume average diameter of the prepared toner particles may be inthe range of about 3 to 8 μm and preferably about 5 to about 8 μm. Whenthe volume average diameter of the toner particles is less than about 3μm, problems of cleaning a photoreceptor and a reduction in yield mayoccur. On the other hand, when the volume average diameter of the tonerparticles is greater than about 8 μm, charging cannot be uniformlyperformed, fusing properties of the toner may be decreased, and aDr-Blade cannot regulate the toner layer.

We further provide a method of forming images. This includes: attachingthe toner to a surface of a photoreceptor on which an electrostaticlatent image, which forms a visible image. The visible image is thentranferred to a transfer medium. The toner is an electrophotographictoner including a latex, a colorant, a wax and about 3-1,000 ppm of eachof Si and Fe. The molar ratio of Si/Fe is in the range of about 0.2 to0.8, and the fusing properties of the electrophotographic toner satisfyFormulas 1 and 2:

$\begin{matrix}{\frac{M\; F\; T_{A}}{M\; F\; T_{B}} \geq {\frac{{HOT}_{A}}{{HOT}_{B}} \times 0.8}} & {{Formula}\mspace{14mu} 1} \\{{\frac{M\; F\; T_{A}}{M\; F\; T_{B}} \times {Gloss}_{A}} \geq {\frac{{HOT}_{A}}{{HOT}_{B}} \times 4}} & {{Formula}\mspace{14mu} 2}\end{matrix}$

MFT_(A) is a minimum fusing temperature in a low-speed printingoperation conducted at a rate of about 160 mm/sec. MFT_(B) is a minimumfusing temperature in a high-speed printing operation conducted at arate of about 290 mm/sec. HOT_(A) is a hot offset temperature in alow-speed printing operation conducted at a rate of about 160 mm/sec.HOT_(B) is a hot offset temperature in a high-speed printing operationconducted at a rate of about 290 mm/sec, and Gloss_(A) is glossinessmeasured at an angle of 60° at a fusing temperature of about 160° C. ina low-speed printing operation conducted at a rate of about 160 mm/sec.

A representative electrophotographic image forming process may includeforming images on a receptor, including charging, exposure to light,developing, transferring, fusing, cleaning, and erasing.

In the charging process, a surface of a photoreceptor is charged withnegative or positive charges, whichever is desired, by a corona or acharge roller. In the light exposing process, an optical system,conventionally a laser scanner or an array of diodes, selectivelydischarges the charged surface of the photoreceptor in an imagewisemanner corresponding to a final visual image formed on a final imagereceptor to form a latent image. The optical system uses electromagneticradiation, also referred to as “light”, which can be infrared lightirradiation, visible light irradiation, or ultra-violet lightirradiation.

In the developing process, suitably charged toner particles generallycontact the latent image of the photoreceptor, and conventionally, anelectrically-biased developer having identical potential polarity to thetoner polarity is used. The toner particles move to the photoreceptorand are selectively attached to the latent image by electrostatic forceto form a toner image on the photoreceptor.

In the transferring process, the toner image is transferred to the finalimage receptor from the photoreceptor, and sometimes, an intermediatetransferring element is used to aid the transfer of the toner image fromthe photoreceptor to the final image receptor.

In the fusing process, the toner image of the final image receptor isheated and the toner particles thereof are softened or melted, therebyfusing the toner image to the final image receptor. In another fusingmethod, the toner is fused on the final image receptor with highpressure by applying or not applying heat.

In the cleaning process, the residual toner remaining on thephotoreceptor is removed.

Finally, in the erasing process, charges of the photoreceptor areexposed to light of a predetermined wavelength band and are reduced tobe substantially uniform and of low value, and thus the residue of theorganic latent image is removed and the photoreceptor is prepared for anext image forming cycle.

We further provide an image forming device including: a photoreceptor; adeveloping unit that transfers toner onto the surface of thephotoreceptor; a toner supplying unit that supplies the toner to thedeveloping unit; and a toner storing unit that stores the toner to besupplied to the toner supplying unit. The toner maybe anelectrophotographic toner including a latex, a colorant, a wax, andabout 3 to about 1,000 ppm of each of Si and Fe. A molar ratio of Si/Femay be in the range of about 0.1 to about 5, and fusing properties ofthe electrophotographic toner satisfy Formulas 1 and 2:

$\begin{matrix}{\frac{M\; F\; T_{A}}{M\; F\; T_{B}} \geq {\frac{{HOT}_{A}}{{HOT}_{B}} \times 0.8}} & {{Formula}\mspace{14mu} 1} \\{{\frac{M\; F\; T_{A}}{M\; F\; T_{B}} \times {Gloss}_{A}} \geq {\frac{{HOT}_{A}}{{HOT}_{B}} \times 4}} & {{Formula}\mspace{14mu} 2}\end{matrix}$

MFT_(A) is a minimum fusing temperature in a low-speed printingoperation conducted at a rate of about 160 mm/sec. MFT_(B) is a minimumfusing temperature in a high-speed printing operation conducted at arate of about 290 mm/sec. HOT_(A) is a hot offset temperature in alow-speed printing operation conducted at a rate of about 160 mm/sec.HOT_(B) is a hot offset temperature in a high-speed printing operationconducted at a rate of about 290 mm/sec. Gloss_(A) is glossinessmeasured at an angle of 60° at a fusing temperature of 160° C. in alow-speed printing operation conducted at a rate of about 160 mm/sec.

We still further provide an image forming apparatus including: anorganic photoreceptor; an image forming unit that forms an electrostaticlatent image on a surface of the organic photoreceptor; a unit thatreceives toner; a toner supplying unit that supplies the toner onto thesurface of the organic photoreceptor in order to form a toner image bydeveloping the electrostatic latent image; and a toner transferring unitthat transfers the toner image to a transfer medium from the surface ofthe organic photoreceptor. The toner may be an electrophotographic tonerincluding a latex, a colorant, a wax, and about 3 to about 1,000 ppm ofeach of Si and Fe. The molar ratio of Si/Fe is in the range of about 0.1to about 5, and fusing properties of the electrophotographic tonersatisfy Formulas 1 and 2:

$\begin{matrix}{\frac{M\; F\; T_{A}}{M\; F\; T_{B}} \geq {\frac{{HOT}_{A}}{{HOT}_{B}} \times 0.8}} & {{Formula}\mspace{14mu} 1} \\{{\frac{M\; F\; T_{A}}{M\; F\; T_{B}} \times {Gloss}_{A}} \geq {\frac{{HOT}_{A}}{{HOT}_{B}} \times 4}} & {{Formula}\mspace{14mu} 2}\end{matrix}$

MFT_(A) is a minimum fusing temperature in a low-speed printingoperation conducted at a rate of about 160 mm/sec. MFT_(B) is a minimumfusing temperature in a high-speed printing operation conducted at arate of about 290 mm/sec. HOT_(A) is a hot offset temperature in alow-speed printing operation conducted at a rate of about 160 mm/sec.HOT_(B) is a hot offset temperature in a high-speed printing operationconducted at a rate of about 290 mm/sec. Gloss_(A) is glossinessmeasured at an angle of 60° at a fusing temperature of 160° C. in alow-speed printing operation conducted at a rate of about 160 mm/sec.

FIG. 1 illustrates an image forming apparatus employing toner preparedaccording to an embodiment of the disclosure.

Referring to FIG. 1, a developer 8, which is a nonmagnetic one-componentdeveloper contained in a developing unit 4, is supplied to a developingroller 5 through a feeding roller 6 formed of an elastic material suchas a polyurethane foam or sponge. The developer 8 supplied to thedeveloping roller 5 reaches a contact point between the developingroller 5 and a developer regulation blade 7 as the developing roller 5rotates. The developer regulation blade 7 is formed of an elasticmaterial such as a flexible metal or rubber. When the developer 8 passesthe contact point between the developing roller 5 and the developerregulation blade 7, the developer 8 is smoothed to form a thin layerthat is sufficiently charged. The developing roller 5 transfers the thinlayer of the developer 8 to a developing domain of a photoreceptor 1where the thin layer of the developer 8 is developed on an electrostaticlatent image of the photoreceptor 1, which is a latent image carrier.The electrostatic latent image is formed by scanning light 3 onto thephotoreceptor 1.

The developing roller 5 and the photoreceptor 1 face each other with apredetermined distance therebetween. The developing roller 5 rotatescounterclockwise and the photoreceptor 1 rotates clockwise.

The developer 8 transferred to the developing domain of thephotoreceptor 1 forms a toner image by developing an electrostaticlatent image on the photoreceptor 1 according to the intensity of theelectric charge generated due to a difference between an AC voltagesuperposed with a DC voltage applied to the developing roller 5 and alatent image potential of the photoreceptor 1 that is charged by acharging unit 2.

The developer 8 developed on the photoreceptor 1 is transferred to atransferring means 9 as the photoreceptor 1 rotates. The developer 8developed on the photoreceptor 1 is transferred to a sheet of paper 13by a corona discharge or a roller to which a high voltage havingopposite polarity to that of the developer 8 is applied as the paper 13passes through the developer 8 developed on the photoreceptor 1, andthus an image is formed.

The image transferred to the printing paper 13 is fused to the printingpaper 13 when it passes through a high-temperature and high-pressurefusing device (not shown). Meanwhile, developer 8′ remaining on thedeveloping roller 5 and which is not developed is transferred back tothe feeding roller 6 contacting the developing roller 5. The remainingdeveloper 8′ that is undeveloped on the photoreceptor 1 is collected bya cleaning blade 10. The above processes are repeated.

The disclosure will be described in more detail with reference to theexamples below, but is not limited thereto. The following examples arefor illustrative purposes only and are not intended to limit the scopeof the disclosure.

Example 1 Synthesis of Latex

A monomer mixture including 970 g of styrene, 192 g of n-butyl acrylate,and 36 g of b-carboxyethyl acrylate (Sipomer, Rhodia), 4.2 g of A-decanediol diacrylate as a cross-linking agent, and 18.8 g of dodecane diol asa chain transfer agent (CTA) were added to a 3 L beaker. 500 g of sodiumdodecyl sulfate (Aldrich) aqueous solution (2 wt % based on water) as anemulsifier was added to the beaker, and the mixture was stirred toprepared a monomer emulsion. 300 g of 5% KPS aqueous solution as aninitiator and 650 g of sodium dodecyl sulfate (Aldrich) aqueous solution(0.13 wt % based on water) as the emulsifier were added to a doublejacketed reactor which was heated to 75° C. The monomer emulsion wasgradually added to the double jacketed reactor while stirring for over 2hours. The mixture was reacted at the same temperature for 8 hours toprepare latex. The particle size of the prepared latex, which wasmeasured using a light scattering method using Horiba 910, was 150-200nm.

Example 2 Preparation of Pigment Dispersion

10 of a mixture of an anionic reactive emulsifier (HS-10; Dai-ich kogyo,Co., Ltd.) and a nonionic reactive emulsifier (RN-10; Dai-ich kogyo,Co., Ltd.) in weight ratios shown in Table 2 below, 60 g of pigment(black, cyan, magenta, and yellow), and 400 g of glass beads having adiameter of 0.8-1 mm were added to a milling bath. Then, the mixture wasmilled at room temperature to prepare a dispersion using a ultrasonichomogenizer.

TABLE 2 HS-10:RN-10 Color Pigment (Weight ratio) Conditions 100:0  K-ABlack Mogul-L 80:20 K-B  0:100 K-C 100:0  Y-A Yellow PY-74 50:50 Y-B 0:100 Y-C 100:0  M-A Magenta PR-122 50:50 M-B  0:100 M-C 100:0  C-ACyan PB 15:4 80:0  C-B 70:30 C-C

Example 3 Agglomeration and Preparation of Toner

500 g deionized water, 150 g of the first latex for a core, 35 g of thecyan pigment dispersion (HS-10 100%), and 27 g of a wax dispersion P-280(

(

)) were added to a 1 L reactor. A mixture of 15 g of PSI-025 (

(

)) and 15 g of nitric acid (0.3 mol) was added to the reactor. Themixture was stirred at 11,000 rpm for 6 minutes using a homogenizer toprepare a first agglomerated toner having particles with a diameter of1.5-2.5 μm. The resultant was added to a IL double jacketed reactor, andheated from room temperature to 50° C. (Tg of the latex-5° C.) at a rateof 0.5° C. per minute. When the particle size is about 5.8 μm, 50 g ofthe second latex prepared by polymerizing styrene-based polymerizablemonomer was added thereto. When a volume average diameter (D50) of theparticles reached 6.0 μm, NaOH (1 mol) was added thereto to adjust thepH to 7. When the D 50 of the particles was constantly maintained for 10minutes, the temperature was increased to 96° C. at a rate of 0.5°C./min. When the temperature reached 96° C., 0.3 mol of nitric acid wasadded thereto to adjust the pH to 6.6. Then, the resultant wasagglomerated for 3-5 hours to obtain a second agglomerated toner havinga particles with a diameter of 5-6 μm in a potato-shape. Then, thesecond agglomerated toner was cooled to a temperature lower than Tg,filtered to be separated, and dried.

The dried toner particles were subjected to a surface treatment byadding 0.5 parts by weight of NX-90 (Nippon Aerosil), 1.0 parts byweight of RX-200 (Nippon Aerosil), and 0.5 parts by weight of SW-100(Titan Kogyo), and the mixture was stirred in a mixer (KM-LS2K, Dae HwaTech Co., Ltd.) at 8,000 rpm for 4 minutes. As a result, toner havingD50 of 5.9 was obtained.

Example 4

Toner was prepared in the same manner as in Example 3, except that acyan pigment was used instead of the black pigment.

Example 5

Toner was prepared in the same manner as in Example 3, except that amagenta pigment was used instead of the black pigment.

Example 6

Toner was prepared in the same manner as in Example 3, except that ayellow pigment was used instead of the black pigment.

Comparative Example 1

Cyan toner (Model No. 5440) manufactured by Konica Minolta Holdings,Inc. was used.

Comparative Example 2

Black Toner (Model No. C4300) manufactured by Konica Minolta Holdings,Inc. was used.

Comparative Example 3

Magenta toner (Model No. C4300) manufactured by Konica Minolta Holdings,Inc. was used.

Evaluation of Fusing Range of Toner

-   -   Device: belt-type fusing device    -   Image for test: 100% pattern    -   Test temperature: 100 to 250° C. (10° C. interval)    -   Speed: 160 mm/sec (for 26 ppm), 290 mm/sec (for 45 ppm)    -   Dwell time: 0.08 sec

Tests were conducted under the conditions described above and theproperties of fused images were evaluated as follows.

Optical density (OD) of a fused image was measured. 3M 810 tape wasattached to the image and the tape was rubbed 5 times using 500 gweight. After the tape was removed, OD of the image was measured.

Fixation rate (%)=(OD of image after removing tape/OD of image beforeremoving tape)×100.

A region having a fixation rate greater than 90% is regarded as thefusing range of toner.

MFT: minimum fusing temperature [minimum temperature exhibiting afixation rate greater than 90% without cold-offset].

HOT: hot offset temperature [minimum temperature at which hot-offsetoccurs].

Evaluation of Glossiness of Toner

Glossiness was measured using a glossmeter at each fusing temperatureusing the above-mentioned fusing device.

Angle: 60°

Pattern: 100% pattern

Evaluation of storage properties at high temperature

100 g of toner was subjected to surface treatment, supplied to adeveloping device, sealed, and stored in a constant temperature-humidityoven under conditions as follows:

23° C., 55% RH (relative humidity) 2 hr

=40° C., 90% RH 48 hr

=50° C., 80% RH 48 hr

=40° C., 90% RH 48 hr

=23° C., 55% RH 6 hr

After stored, caking of toner in the developing device was observed withthe naked eye, and 100% images were printed. The quality of the imageswas observed, and the results are shown in Table 3 below.

TABLE 3 storage properties at MFT_(A) MFT_(B)° C. HOT_(A) HOT_(B) high(° C.) (° C.) (° C.) (° C.) Gloss_(A) Gloss_(B) Latitude_(A)Latitude_(B) temperature Example 3 130 150 250 250 7.3 6.1 120 100 ∘Example 4 140 150 250 250 8.2 7.4 110 100 ∘ Example 5 140 150 250 2507.5 6.1 110 100 ∘ Example 6 120 140 250 250 10.7 7.0 130 110 ∘Comparative 140 175 250 240 3.2 1.9 110 65 Δ Example 1 Comparative 130170 240 220 4.4 3.1 110 50 x Example 2 Comparative 130 180 200 200 5.53.7 70 20 x Example 3 —: Reference of evaluation ∘: Good image quality,No-Caking Δ: Poor image quality, No-Caking x: Caking

MFT_(A): minimum fusing temperature in a low-speed printing operationconducted at a rate of about 160 mm/sec (26 ppm).

MFT_(B): minimum fusing temperature in a high-speed printing operationconducted at a rate of about 290 mm/sec (45 ppm).

HOT_(A): hot offset temperature in a low-speed printing operationconducted at a rate of about 160-mm/sec (26 ppm).

HOT_(B): hot offset temperature in a high-speed printing operationconducted at a rate of about 290 mm/sec (45 ppm).

Gloss_(A): glossiness measured in a low-speed printing operationconducted at a rate of about 160 mm/sec (26 ppm) (at an angle of 60° ata fusing temperature of 160° C.).

Gloss_(B): glossiness measured in a high-speed printing operationconducted at a rate of about 290 mm/sec (45 ppm) (at an angle of 60° ata fusing temperature of 160° C.).

Latitude_(A): HOT_(A)−MFT_(A)

Latitude_(B): HOT_(B)−MFT_(B)

As shown in Table 3 above, toner prepared according to Examples 3 to 6has excellent storage properties at high temperature and excellentglossiness, and the glossiness difference between low-speed printing andhigh-speed printing is less than 1. Thus, it can be seen that the toneraccording to Examples 3 to 6 satisfies Formulas 1 and 2.

The rheological properties of toner were measured using a temperaturesweep in which the temperature is programmed to increase at constantfrequency and a frequency sweep in which the frequency is programmed tochange at constant temperature. The conditions are as follows.

Temperature sweep: device: TA ARES, temperature increase rate: 2°C./min, 40-180° C., frequency: 6.28 rad/s.

Frequency sweep: device: TA ARES, temperature: 140° C., frequency0.1-100 rad/s.

The storage modulus G′ of the temperature sweep of toner preparedaccording to Examples 3 to 6 was respectively 2E+05 to 3E+05 Pa·s at 80°C. and 5E+02˜2E+03 Pa·s at 140° C.

The slope of linear regions in the frequency sweep curve was −0.4 to−0.2 at 140° C.

A metal salt agglomerating agent including Si and Fe is used toagglomerate toner. Thus, toner can efficiently agglomerate at a lowtemperature using a small amount of the metal salt agglomerating agent,and an organic color pigment such as rhodamine pigment, which does noteasily agglomerate, can agglomerate. In addition, risks that aluminumremaining in conventional agglomerating agents harms humans and theenvironment can be excluded. According to the agglomeration processregulation, capsule-shaped toner can be prepared, and thus the chargingproperties may be uniformly regulated and fluidity and heat preservingproperties of toner may be improved by inhibiting the colorant andpigment from being exposed. Furthermore, since the fusing properties oftoner are not sensitively affected by the printing speed, toner can havestable fusing properties in a high-speed printing operation, and thustoner for both low-speed and high-speed fusing devices can be prepared.

While the disclosure has been particularly shown and described withreference to representative examples thereof, it will be understood bythose of ordinary skill in the art that various changes in form anddetails may be made therein without departing from the spirit and scopeof the disclosure as defined by the following claims.

1. An electrophotographic toner comprising: a latex, a colorant, a wax;and about 3 to about 1,000 ppm each of Si and Fe, and having a molarratio of Si/Fe of about 0.1 to about 5, wherein fusing properties of theelectrophotographic toner satisfy Formulas 1 and 2: $\begin{matrix}{{\frac{M\; F\; T_{A}}{M\; F\; T_{B}} \geq {\frac{{HOT}_{A}}{{HOT}_{B}} \times 0.8}},} & {{Formula}\mspace{14mu} 1} \\{{{\frac{M\; F\; T_{A}}{M\; F\; T_{B}} \times {Gloss}_{A}} \geq {\frac{{HOT}_{A}}{{HOT}_{B}} \times 4}},} & {{Formula}\mspace{14mu} 2}\end{matrix}$ wherein MFT_(A) is a minimum fusing temperature in alow-speed printing operation conducted at a rate of about 160 mm/sec,wherein MFT_(B) is a minimum fusing temperature in a high-speed printingoperation conducted at a rate of about 290 mm/sec, wherein HOT_(A) is ahot offset temperature in a low-speed printing operation conducted at arate of about 160 mm/sec, wherein HOT_(B) is a hot offset temperature ina high-speed printing operation conducted at a rate of about 290 mm/sec,and wherein Gloss_(A) is glossiness measured at an angle of about 60° ata fusing temperature of about 160° C. in a low-speed printing operationconducted at a rate of about 160 mm/sec.
 2. The electrophotographictoner of claim 1, wherein a maximum glossiness difference of theelectrophotographic toner between low-speed printing and high-speedprinting is less than 1 when an image is fused.
 3. Theelectrophotographic toner of claim 1, wherein when theelectrophotographic toner is measured using a differential scanningcalorimeter, a starting point of the highest endothermic peak is in therange of about 68° C. to about 75° C. and the peak temperature is in therange of about 75° C. to about 95° C.
 4. The electrophotographic tonerof claim 1, having an average particle diameter in the range of about 3μm to about 8 μm.
 5. The electrophotographic toner of claim 1, having anaverage sphericity in the range of about 0.940 to about 0.970.
 6. Theelectrophotographic toner of claim 1, wherein an average sphericitydifference between electrophotographic toner having an average particlediameter of about 2 μm and about 5 μm s less than about 0.020.
 7. Theelectrophotographic toner of claim 1, having a PSDv and a PSDp less thanabout 1.25.
 8. The electrophotographic toner of claim 1, comprising nomore than about 20 parts by weight of the wax based on 100 parts byweight of the toner.
 9. The electrophotographic toner of claim 1,wherein the latex is comprised of a first latex particle as a core, thefirst latex particle comprised of the wax, colorant, Si and Fe andwherein the latex is comprised of a second latex particle as a shell,wherein the second latex particle is coated on the first latex particle.10. The electrophotographic toner of claim 9, wherein the shell of thelatex is comprised of a third latex particle coated on the second latexparticle.
 11. A method for preparing an electrophotographic toner, themethod comprising: preparing a first agglomerated toner by mixing firstlatex particles, the first latex particles comprising a wax with apigment dispersion, and adding a metal salt of Si and Fe to the mixture;and preparing a second agglomerated toner by agglomerating fineparticles by coating a second latex on the first agglomerated toner,wherein the fusing properties of the electrophotographic toner satisfyFormulas 1 and 2 $\begin{matrix}{{\frac{M\; F\; T_{A}}{M\; F\; T_{B}} \geq {\frac{{HOT}_{A}}{{HOT}_{B}} \times 0.8}};} & {{Formula}\mspace{14mu} 1} \\{{{\frac{M\; F\; T_{A}}{M\; F\; T_{B}} \times {Gloss}_{A}} \geq {\frac{{HOT}_{A}}{{HOT}_{B}} \times 4}},} & {{Formula}\mspace{14mu} 2}\end{matrix}$ wherein MFT_(A) is a minimum fusing temperature in alow-speed printing operation conducted at a rate of about 160 mm/sec,wherein MFT_(B) is a minimum fusing temperature in a high-speed printingoperation conducted at a rate of about 290 mm/sec, wherein HOT_(A) is ahot offset temperature in a low-speed printing operation conducted at arate of about 160 mm/sec, wherein HOT_(B) is a hot offset temperature ina high-speed printing operation conducted at a rate of about 290 mm/sec,and wherein Gloss_(A) is glossiness measured at an angle of 60° at afusing temperature of 160° C. in a low-speed printing operationconducted at a rate of about 160 mm/sec.
 12. The method of claim 11,further comprising: preparing a third latex by polymerizing at least onepolymerizable monomer; and coating the third latex on the secondagglomerated toner.
 13. The method of claim 11, further comprising,before the mixing first latex particles step, preparing the first latexparticles by mixing polyester particles and polymer particles preparedby polymerizing at least one polymerizable monomer.
 14. The method ofclaim 11, wherein the first latex particles are comprised of the wax andthe first latex particles.
 15. The method of claim 11, furthercomprising adding about 3 to about 1,000 ppm each of Si and Fe as themetal salt during the preparing a first agglomerated toner step.
 16. Themethod of claim 11, wherein the Si and Fe are added at a pH of 1 to 4and wherein the second latex is coated on the first agglomerated tonerat a pH of 6 to
 8. 17. A method of forming images, comprising: attachinga toner to a surface of a photoreceptor on which an electrostatic latentimage has been formed to form a visible image; and transferring thevisible image to a transfer medium, wherein the toner is anelectrophotographic toner comprising a latex, a colorant, a wax, andabout 3 to about 1,000 ppm each of Si and Fe, and has a molar ratio ofSi/Fe of about 0.1 to about 5, wherein fusing properties of theelectrophotographic toner satisfy Formulas 1 and 2: $\begin{matrix}{{\frac{M\; F\; T_{A}}{M\; F\; T_{B}} \geq {\frac{{HOT}_{A}}{{HOT}_{B}} \times 0.8}};} & {{Formula}\mspace{14mu} 1} \\{{{\frac{M\; F\; T_{A}}{M\; F\; T_{B}} \times {Gloss}_{A}} \geq {\frac{{HOT}_{A}}{{HOT}_{B}} \times 4}},} & {{Formula}\mspace{14mu} 2}\end{matrix}$ wherein MFT_(A) is a minimum fusing temperature in alow-speed printing operation conducted at a rate of about 160 mm/sec,wherein MFT_(B) is a minimum fusing temperature in a high-speed printingoperation conducted at a rate of about 290 mm/sec, wherein HOT_(A) is ahot offset temperature in a low-speed printing operation conducted at arate of about 160 mm/sec, wherein HOT_(B) is a hot offset temperature ina high-speed printing operation conducted at a rate of about 290 mm/sec,and wherein Gloss_(A) is glossiness measured at an angle of 60° at afusing temperature of about 160° C. in a low-speed printing operationconducted at a rate of about 160 mm/sec.
 18. An image forming devicecomprising: a photoreceptor; an image forming unit that forms anelectrostatic latent image on a surface of the photoreceptor; a unitthat receives toner; a toner supplying unit that supplies the toner ontothe surface of the photoreceptor in order to form a toner image bydeveloping the electrostatic latent image; a toner transferring unitthat transfers the toner image to a transfer medium from the surface ofthe photoreceptor, wherein the toner is an electrophotographic tonercomprising a latex, a colorant, a wax, and about 3 to about 1,000 ppmeach of Si and Fe, and has a molar ratio of Si/Fe of about 0.1 to about5, and wherein fusing properties of the electrophotographic tonersatisfy Formulas 1 and 2: $\begin{matrix}{{\frac{M\; F\; T_{A}}{M\; F\; T_{B}} \geq {\frac{{HOT}_{A}}{{HOT}_{B}} \times 0.8}};} & {{Formula}\mspace{14mu} 1} \\{{{\frac{M\; F\; T_{A}}{M\; F\; T_{B}} \times {Gloss}_{A}} \geq {\frac{{HOT}_{A}}{{HOT}_{B}} \times 4}},} & {{Formula}\mspace{14mu} 2}\end{matrix}$ wherein MFT_(A) is a minimum fusing temperature in alow-speed printing operation conducted at a rate of about 160 mm/sec,wherein MFT_(B) is a minimum fusing temperature in a high-speed printingoperation conducted at a rate of about 290 mm/sec, wherein HOT_(A) is ahot offset temperature in a low-speed printing operation conducted at arate of about 160 mm/sec, wherein HOT_(B) is a hot offset temperature ina high-speed printing operation conducted at a rate of about 290 mm/sec,and wherein Gloss_(A) is glossiness measured at an angle of 60° at afusing temperature of 160° C. in a low-speed printing operationconducted at a rate of 160 mm/sec.
 19. A developing device comprising: aphotoreceptor; a developing unit that transfers toner onto the surfaceof the photoreceptor; a toner supplying unit that supplies the toner tothe developing unit; and a toner storing unit that stores the toner tobe supplied to the toner supplying unit, wherein the toner is anelectrophotographic toner comprising a latex, a colorant, a wax, andabout 3 to about 1,000 ppm each of Si and Fe, and has a molar ratio ofSi/Fe of about 0.1 to about 5, and wherein fusing properties of theelectrophotographic toner satisfy Formulas 1 and 2: $\begin{matrix}{{\frac{M\; F\; T_{A}}{M\; F\; T_{B}} \geq {\frac{{HOT}_{A}}{{HOT}_{B}} \times 0.8}};} & {{Formula}\mspace{14mu} 1} \\{{{\frac{M\; F\; T_{A}}{M\; F\; T_{B}} \times {Gloss}_{A}} \geq {\frac{{HOT}_{A}}{{HOT}_{B}} \times 4}},} & {{Formula}\mspace{14mu} 2}\end{matrix}$ wherein MFT_(A) is a minimum fusing temperature in alow-speed printing operation conducted at a rate of about 160 mm/sec,wherein MFT_(B) is a minimum fusing temperature in a high-speed printingoperation conducted at a rate of about 290 mm/sec, wherein HOT_(A) is ahot offset temperature in a low-speed printing operation conducted at arate of 160 mm/sec, wherein HOT_(B) is a hot offset temperature in ahigh-speed printing operation conducted at a rate of about 290 mm/sec,and wherein Gloss_(A) is glossiness measured at an angle of 60° at afusing temperature of 160° C. in a low-speed printing operationconducted at a rate of about 160 mm/sec.